The methylene blue staining procedure is used to measure yeast viability based on the assumption that the methylene blue will enter the cells and be broken down by living yeast cells that produce the enzymes which breaks down methylene blue, leaving the cells colourless. The non- viable cells do not produce this enzyme (or enzymes) and as such the methylene blue that enters the cells are undegraded causing the cells to remain coloured (the oxidized form concentrates intracellularly). The coloured and colourless cells are then counted using a haemocytometer and the number of viable and nonviable cells determined in a given area, the result would be then used to estimate the number of cells in the original sample. This is an easy, quick and cheap method to determine the amount of viable yeast present in a sample though this is not the best method for a number of reasons. A major reason is that methylene blue rapidly becomes toxic to the yeast and as such preparations should be examined within 10 minutes of preparation. The older the cells become, the less likely that they are to take up the methylene blue dye from solution since as the yeast age, they deposit lipid and/or sugar in their cell membrane (in the form of free sterols[predominantly ergosterol and zymosterol with minor portions of lanosterol and fecosterol] and phospholipids[phosphotidylcholine and phosphotidylethanolamine with minor portions of phosphotidylinositol, phosphotidylserine and phosphotidyl-glycerol]) as a survival mechanism to protect their internal mechanisms from the buildup of waste in the external environment. This means that cells which are not viable would not take up the dye and due to their age and not their ability to break down the methylene blue (as a result of their viability) would remain colourless and be determined to be viable (a false positive). The test itself is also not very accurate since yeast might not be evenly distributed in the original sample and depending on the...

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...Stainin
g
What is Cellular Staining?
Cell staining is a technique that can be used to
better visualize cells and cell components
under a microscope. By using different stains,
one can preferentially stain certain cell
components, such as a nucleus or a cell wall,
or the entire cell. Most stains can be used on
fixed, or non-living cells, while only some can
be used on living cells; some stains can be
used on either
living is
or non-living
What
Cellularcells.Staining?
The most basic reason that cells are stained
is to enhance visualization of the cell or
certain cellular components under a
microscope. Cells may also be stained to
highlight metabolic processes or to
differentiate between live and dead cells in a
SIMPLE STAINING
1.
2.
3.
4.
5.
6.
1.
2.
Begin by obtaining a clean microscope
slide.
Place the specimen on the center of the
slide.
Add a couple of drop of stain.
Put a cover slip on the top of the slide
with a 45 degree angle.
Remove some of the excess stain that’s
on the slide using a tissue paper.
To finish,
view your slide
on the
COMPLEX
STAINING
microscope.
Clean
and dry microscope slides
thoroughly.
Flame the surface in which the smear is
to be spread.
COMPLEX STAINING
3.
4.
5.
6.
7.
8.
Flame the inoculating loop.
Transfer a loop full of tap water to the
flamed slide surface.
Reflame the loop making sure the entire
length of the wire that will enter the
tube has been...

...Abdulaziz
Design Lab Report
Research Question:
How is the rate of yeast fermentation of 7.5g of yeast affected by using different companies of yeast (Bakon Yeast Inc., Lake States Yeast LLC, Lesaffre Yeast Corp, Red Star Yeast Company, and Minn-Dak Yeast CO Inc.)?
Background Information:
Yeast is a fungal microorganism that is used to manufacture mainly bread and beer. It reproduces rapidly. Fermentation is the process by which yeast takes in sugar and releases alcohol and carbon dioxide. Fermentation requires a mostly a damp and wet environment to occur. Different yeasts respond differently to changes in environment, making some better for baking and others for brewing. Bakers use fermentation to add CO2 bubbles to bread dough. During baking, these bubbles make the bread light expands while the alcohol boils away. Brewers take care to preserve the alcohol of fermentation and use the CO2 to help build a frothy head for their potent beverages.
Yeast Fermentation is controlled by some factors:
Temperature – Enzymes that work on the yeast and ferment it, work in a specific temperature. If the temperature of the yeast and its surrounding is low, then the enzymes will not act on the yeast and the yeast will not ferment. But when the temperature...

...experiment to demonstrate the effect of temperature on fermentation by yeast
The purpose of this laboratory is to observe how temperature affects the metabolism of
Grape juice by visibly noting the volume changes of identical food mixes containing yeast at different temperatures.
Background Information
If yeast is added to a liquid containing sugar and other nutrients, kept at an appropriate temperature (and deprived of oxygen), it will turn the sugars into ethanol (alcohol) and carbon dioxide.
Apparatus and Materials
Waterbaths set to a range of values - 10, 20, 30, 40, 50, 60, 70 °C
Thermometer
1 x 200 ml beaker - preferably marked on side
7 x test tubes
7 x 10 ml measuring cylinders
7 x Rubber bungs to fit the measuring cylinder & test tubes
Forceps
700 ml grape juice (Red)
70 ml yeast suspension
Plastic rod for mixing
Ice
Method
Step Method Justification
1 Prior to the experiment, make sure that the grape juice is shaken or mixed.
2 Set up a waterbath of 10 °C of the above. Place a thermometer in the waterbath.
3 Add either ice or hot water, to the waterbath to make sure the required temperature in achieved.
4 Measure out 100 ml the grape juice into the 200 ml beaker using markings on the side of the beaker as a guide.
5 Pour the contents of the 200 ml beaker in a measuring cylinder
6 Mix the yeast suspension using the plastic rod, and add 10 ml of the...

...Dinah Gibson
Ms. Lunsford
Honors Chemistry
12/6/2011
Abstract
Yeast is widely used for making bread, beer, and wine. People all over the world drink and eat those products. This projects looks at which fruit juice with a higher percentage of sugar will produce more fermentation. The original purpose of this experiment was to determine the amount of fermentation of 3 different fruit juices after adding a certain amount of yeast. By measuring the type of fruit juice (independent variable) the amount of fermentation as shown by the reduction of sugar (dependent variable).My hypothesis my hypothesis is that the fruit juice with a higher percentage of sugar will produce more fermentation. The experimental results supported my hypothesis by showing that the results indicate that this hypothesis should be accepted, because the orange juice, which had the highest sugar content, produced the most fermentation. Because of the results of this experiment, I wonder if using more yeast would produce more fermentation or if using another type of juice with two of them mixed together like the cranberry-grape juice, would produce less fermentation.
The Effect of Yeast on Different Fruit Juices
Question: what’s the effect of different juice on yeast?
Variable: The manipulated variable was the type of fruit juice.
The responding variable was the amount of fermentation as shown by the...

... YEAST LAB REPORT
Respiration occurs to everything that is living, and it can happen during day and night. Most cells use aerobic cellular respiration, but some others are anaerobic. In anaerobic organisms do not use oxygen to break down glucose or have limited supplies. The energy released from glucose is converted into ATP to function and survive. The organelle, where aerobic respiration happens is the mitochondrion. Anaerobic respiration happens in the cytoplasm aerobic or anaerobic respiration is basically fermentation. If we put yeast and sugar in the test tube with warm water then the ballon's circumference will increase.
Materials:
* dry rapid rise yeast
* test tube
* tape measure
* goggles
* sugar
* warm water
* apron
* clock stop watch
* electronic scale
* metric tape measure
* masking tape
In this laboratory experiment, the class' purpose was to fill a test tube with 4g of yeast and 8g of sugar. After that we would add to the test tube, 3/4 of warm water. After adding all the ingredients, we put a stretched ballon over the test tube, then we made sure the ballon is tight and add masking tape to it just to make sure. Shake the test tube to make the ingredients mix. Most important of all measure the diameter of the ballon every 2 minutes for a total of 20 minutes. Record the data in a chart.
At the end of the experiment, we made a conclusion that our hypothesis...

...﻿Yeast Population Lab Report
During this experiment we were trying to determine how food availability affects CO2 production (related to population growth). We investigated how one factor influences the change in yeast population growth as measured by the amount of carbon dioxide produced.
The yeast that you buy in the store contains living organisms–invisible small one celled, microorganisms. As long as they are kept dry, they are inactive. When they are given food, moisture and warmth, they become active and carry out many of the life activities larger organisms do. Molasses, which you can also buy, is a mixture of substances that are obtained from sugar cane. Though the substances are not alive, they were made by living organisms, the sugar cane plants. Therefore, they are called organic substances. Organic substances as well as organisms themselves are Important to the work of biologists. The organic substances in molasses can be used as food by the yeasts. The factors that can affect yeast growth are temperature (30 degrees Celsius is the optimum temp for yeast growth), nutrients (e.g. sucrose, fructose, glucose, lactose - (does not affect yeast growth), pH level (5 - 6 is the optimum pH level for growth). Fermentation is the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms, typically involving effervescence and the...

...﻿Yeast Fermentation Lab Report
The purpose of this experiment was to observe the process in which cells must partake in a respiration process called anaerobic fermentation and as the name suggests, oxygen is not required. This particular procedure, which is catabolic meaning, it breaks down energy, can be present in to types of fermentation; alcohol in yeast or lactic acid in muscles. This is a continued reaction from glycolysis, where glucose is broken down into three carbon sugars. The products of alcohol fermentation are ethanol and carbon dioxide and the products produced by lactic acid fermentation is lactate.
As we observed the effects of yeast fermentation, it is imperative to know that yeast makes energy through fermentation. Yeast fermentation was combined with several different saccharides such as glucose, sucrose, starch, and fructose. Boiled water was also included in this experiment as another variable. The control was simply a vial of yeast and distilled water at room temperature. Each vial was filled completely with the mixture (the solution was composed of individual saccharides and water) and then the gap was measure in 2 minute increments. The spectrometer was set at a 600 mm absorbance and each vial was measure, once again, in every two minute intervals.
The purpose of this experiment was to better understand the logistics behind the fermentation process. In tube...

...﻿Useful Microbes
Making Bread with Yeast
By Rebecca Coles
Introduction
Bread is such a common food, who would expect it to be made in such a fascinating and clever way? A simple loaf contains just four main ingredients; flour (the main ingredient), warm water (the yeast prefer the water warm), salt and of course the yeast, tiny microscopic fungi that help the bread rise. Although fascinating the process is surprisingly simple; first, the flour, sugar and water is mixed together with yeast to make the bread dough, next the yeast ferments (a chemical change that results in the production of alcohol or gas) natural sugars in the dough to make alcohol and carbon dioxide bubbles. The gas is trapped in the sticky proteins in the mixture and causes it to bubble and rise, whilst the alcohol is converted to compounds which give the bread its taste as it is baked in the oven.
What Is Yeast?
Yeasts consist of only one cell and belong to the kingdom of Fungi. There are an estimated 1,500 species of yeast with the common yeast being Saccharomyces cerevisiae, used for making bread and also beer. Yeasts need sugar to grow. They divide in a process called budding.
When was this Process discovered?
Extensive research shows that Ancient Egypt was the birthplace of the bread we know today. Although now we have modern technology to...